The present invention relates to a scroll type compressor, more particularly to a scroll type compressor that compresses gas supplied to a fuel cell.
There are various types of compressors such as a screw type compressor, a rotary type compressor and a scroll type compressor. Since the scroll type compressor is small, light, and quiet without much vibration and noise, the scroll type compressor is widely used for freezing and air conditioning among others. The scroll type compressor produces heat in a compression cycle. In a prior art as described in Unexamined Japanese Patent Publication No. 8-247056, a cooling chamber is defined to the side which gas in a compression chamber is discharged in order to remove the heat.
FIG. 12 shows a cross-sectional view in an axial direction of a conventional scroll type compressor 100. In the compressor 100, a housing is constituted of a front casing 101, an end plate 102 and a rear casing 103. The end plate 102 is placed on one side of the front casing 101, to which gas is discharged. The rear casing 103 is placed on the other side of the front casing 101 where a motor which is not shown is connected. A discharge port 104 is formed at the center of the front casing 101. A discharge valve 108 which opens toward the end plate 102 side only is provided at the discharge port 104. A gas passage 112 is formed to penetrate the end plate 102 on the side of the discharge port 104, to which the gas is discharged. A cooling chamber 120 is defined between the front casing 101 and the end plate 102. A fixed scroll of a volute shape 105 extends from an inner wall 107 of the front casing 101 to face the side of the motor in a standing manner. On the other hand, a drive shaft 109, which is connected to a rotary shaft of the motor, is in the shape of crank. One end of the drive shaft 109 is rotatably supported by the rear casing 103 on the side of the motor. The other end of the drive shaft 109, to which the gas is discharged, is rotatably supported by an orbital plate 111. An orbital scroll of a volute shape 110 extends from the orbital plate 111 toward the front casing 101. The fixed scroll 105, the inner wall 107, the orbital scroll 110 and the orbital plate 111 cooperatively form compression chambers 106. The compression chambers 106 are defined in a volute shape.
Still referring to FIG. 12, when the drive shaft 109 is rotated by the motor, the orbital scroll 110 orbits. Gas such as air in the compression chambers 106 is moved toward the center of the fixed scroll 105 as is compressed by orbital movement of the orbital scroll 110. The temperature of the gas rises during the compression cycle. Then, the compressed gas is discharged outside the compressor 100 through the discharge port 104 and the gas passage 112.
Coolant such as cooling water flows into the cooling chamber 120 through an inlet which is not shown. The cooling chamber 120 is defined in the vicinity of the compression chambers 106 and the gas passage 112. Therefore, heat of the gas compressed in the compression chambers 106 and the gas discharged into the gas passage 112 is conducted to the coolant. The temperature of the coolant rises due to the heat conduction, and the coolant flows outside the compressor 100 through an outlet which is not shown.
In the above prior art, however, the gas is discharged outside the compressor 100 through the gas passage 112 which extends in the axial direction of the drive shaft 109. The gas passage 112 is short in length. Accordingly, when the discharge gas passes through the gas passage 112, heat exchange between the discharge gas and the coolant in the cooling chamber 120 is not sufficiently performed. Therefore, temperature of the discharge gas is not sufficiently decreased.
When the temperature of the discharge gas is high, if a device whose heat resistance is low is placed in the vicinity of the gas passage 112, the device may have trouble. For example, when the scroll type compressor 100 is used to compress the gas supplied to the fuel cell, a hydrogen ion exchange membrane is placed below the compressor 100. Since the hydrogen ion exchange membrane is low in heat resistance, the discharge gas in high temperature may cause trouble.
Since the discharge gas in high temperature is small in density, mass flow of the gas (kg/hour) decreases. Namely, compression efficiency is lowered. When the discharge gas is utilized, a predetermined mass of the gas per time unit may be required. In this case, if work of the compressor 100 is increased to reserve the predetermined mass of the gas, the compressor 100 or the motor driving the compressor 100 is required to be increased in size.
To decrease the temperature of the discharge gas without changing the work, another heat exchanger may be connected below the scroll type compressor 100. In this case, however, extra space for placing another heat exchanger is required.
The present invention addresses a scroll type compressor whose discharge gas is low in temperature.
According to the present invention, a scroll type compressor includes a housing, a fixed scroll member, a movable scroll member, a discharge port, a cooling chamber and a gas cooler. The fixed scroll member is fixed to the housing. The movable scroll member is accommodated in the housing and defining a compression region with the fixed scroll member where gas is compressed by orbiting the movable scroll member relative to the fixed scroll member. The compressed gas is discharged from the compression region through the discharge port. The cooling chamber for cooling the compressed gas is disposed in the vicinity of the compression region in the housing. The gas cooler for passing the gas discharged from the discharge port extends along the cooling chamber.